Tool having combination seal and shear releasing mechanism



Aug. 25, 1970 r s ETAL 3,525,394

TOOL HAVING COMBINATION SEAL AND SHEAR RELEASING MECHANISM Filed May 28, 1968 2s v 52 Z8 20 Mua I 1 km 24 K) 22 um Hk54 INVENTORS.

United States Patent 07 3,525,394 TOOL HAVING COMBINATION SEAL AND SHEAR RELEASING MECHANISM Charles A. Pitts, Tulsa, Okla., and William R. Lewis, Wichita Falls, Tex., assignors to The Dow Chemical Company, Midland, Mich., a corporation of Delaware Filed May 28, 1968, Ser. No. 732,643 Int. Cl. E2lb 33/00 US. Cl. 166-225 4 Claims ABSTRACT OF THE DISCLOSURE The invention concerns down-hole apparatus for use especially in casing cementing operations wherein a socalled string of casing is lowered into a well bore and cemented in place. The apparatus comprises an insert which is adapted, on the application of suitable pressure, to rupture an O ring sealing a shear-releasing device disposed in abutting channels in the insert wall and the wall of a device surrounding the insert. A ball seal or other flow-closing device is utilized in applying pressure on the insert.

BACKGROUND OF THE INVENTION This invention relates to apparatus used in completing or treating earth wells, and particularly to casing shoe apparatus for use in such wells.

As casing is lowered into an earth well, a shoe at the lower end of the casing is usually provided which has an orifice device coupled across its open end. The orifice device restricts the amount of upward flow of material through the casing as the casing is lowered into the well bore, thus allowing the casing to partially float its way down the well bore.

After the casing is in position, it is desirable to remove the orifice device. In the past, the orifice devices have been removed by first plugging the orifice and then applying pressure against the orifice device to break shear pins which have held the device in place. However, the use of shear pins is troublesome and less reliable in operation than is desired.

Accordingly, a principal object of this invention is to provide an improved down-hole flow controllable orifice device.

Another object of this invention is to provide an improved down-hole tool having a pressure detachable insert member.

In accordance with this invention, there is provided a tool adapted to be attached to a column of tubular elements which comprises an outer wall part adapted to be coupled to a wall of a tubular element and an insert member disposed within said outer wall part and coupled to it by means of a shearable ring element disposed in the space defined by abutting circumferential grooves in the insert member and said outer wall part.

The invention, as well as additional objects and advantages thereof will best be understood when the following detailed description is read in connection with the accompanying drawing, in which:

FIG. 1 is a diagrammatical view, partly in section, of apparatus in accordance with this invention, and

FIG. 2 is an enlarged elevational view, partly in section, of the lower end of the casing shown in FIG. 1.

Referring to the drawing, there is shown casing shoe and orifice flow apparatus, indicated generally by the numeral 10, secured to a string of casing 12 in an earth well which extends from the surface 14 of the earth through sub-surface earth formations 16. The apparatus 18, as illustrated, is near the bottom 36 of the well bore.

A mud reservoir 32 and cement reservoir 30 are couplied through lines 24, 22, respectively, which contain valves 28, 26, respectively, through pump 20 and line 18 to a casing head 34 at the surface or upper end of the casing.

A ball sealing element 48 and a cementing plug 46 are disposed within the casing 12.

The cementing plug 46 is disposed above the ball sealing element 48 and separates the mud 44 from the cement slurry 42 in the casing.

Referring now to the apparatus 10, and particularly to FIG. 2, the apparatus comprises a bushing element 52 having threads on its external surface when engaging the inner surface threads of the lower part of the casing 12. The element 52 has an axial bore 68 into which an orifice element 54 having cylindrically shaped side walls fit closely but slidably. The orifice element 54 has a tapered bore 70 extending therethrough, the narrow part of the taper being at its lower end.

The orifice element 54 and the bushing element 52 each have a recessed channel 62, 64, respectively, in their side walls (the wall of bore 68 in the element 52) which face each other when the parts are assembled. The two channels abut against each other to form, when viewed in cross section a more or less square opening.

An 0 ring seal element, made of any suitable material, preferably an elastic material such as rubber or neoprene, for example, may be used.

A spring loaded closure element 56 extends downwardly within the shoe 50 from the bushing element 52 and is prevented from closing by the downwardly extending spur element 58' which is attached to the underside of the orifice element 54.

In operation, with the apparatus 10 in place at or near the lower end of the casing 12, the small orifice 70, adapted to be a valve seat by virtue of its tapered configuration, restricts the upward flow of mud and/ or fluid from the borehole into the casing. Thus, though the casing doesnt float, as would occur if the lower end of the casing were closed off, it does not act as a dead weight as it is lowered into the bore hold. The casing partially supports its own weight since it displaces more mud and/ or fluid than is admitted into the casing.

After the casing is in position, cement from the reservoir 30 is pumped into the casing 12, the cement passing through the lower end of the casing and entering the annulus (as at 38) between the casing and the well bore wall, displacing upwardly the previously present mud and/ or fluids 40.

During the cemetning operations it is desirable to remove the orifice element 54 from the bushing element 52.

This removal of the orifice element is accomplished by dropping the ball sealer element 48 down the interior of the casing, where it is drawn by the flow of material down the casing and into the tapered orifice 70', where it seats, blocking further flow down the casing.

Pressure is then increased, usually to about 800 pounds per square inch, to an amount sufficient to shear the O ring seal element 66, at which time the orifice element is forced downwardly and, usually, out of the shoe 50.

On removal of the orifice element, any back pressure closes the spring loaded closure element 56 to stop any back flow.

In practice, the cement plug 46 at the upper end of the cement 42 separates the cement from the mud which is used to drive the cement plug downwardly until it rests on the bushing 52.

Thus, from the above it may be seen that the instant invention provides a simple, reliable, easy to use combination seal and shear release assembly.

What is claimed is:

1. A tool adapted to be attached along a column of tubular elements, said tool comprising a bushing part having a top, bottom and outer side walls which are adapted to be coupled across a tubular element and an axial bore extending from said top to said bottom, said bottom having a hinged spring loaded closure element coupled thereto, said axial bore having a circumferential groove therein, an orifice element having an upper part, a lower part, a downwardly extending spur-like element adapted to bear against said closure element, and an outer wall part adapted to telescope within said bushing part, said outer Wall part having a circumferential groove therein which, when said orifice element is operatively telescoped within said bushing part, is aligned with and faces the groove in said bushing part, said orifice part having an axial bore therein which is adapted to be closed in response to external forces, and an O ring element having a cross section greater than either of said grooves, said O ring being disposed in said grooves.

2. Apparatus in accordance with claim 1, wherein said O ring is made of an elastic material.

3. Apparatus in accordance with claim 1, wherein said grooves are disposed perpendicular to the longitudinal axis of said apparatus.

4. Apparatus in accordance with claim 1, wherein said axial bore in said orifice element is tapered with the lower part having a smaller diameter.

References Cited UNITED STATES PATENTS 2,300,854 11/1942 Allen et al 166224 X 3,007,527 11/1961 Nelson 166225 3,011,559 12/1961 Muse et al 166-225 3,275,080 9/1966 Nelson et a1 166225 DAVID H. BROWN, Primary Examiner 

